Xp pro,AMD1800+ 1.50Ghz and1gb of ram. It an older machine that I would like to upgrade rather than buy new, But don't know if it can be done thanks.

We need to know your motherboard, or manufacturer, to advise you fully... and your hard drive.
Usually you can upgrade the video grapics card, hard drive size and speed, memory amount as well as increasing speed a bit. Then with older machines it is always wise to replace the parts that have a lot of wear: Power supply, cpu fan, hard drive and optical drives... which, of course, you can do component by component on a budgeted approach.
Remove the heat sink, to clean and replace the thermal paste.
Check for updates to your software and security system.
Perhaps a new monitor and graphics card combination.
External backup drive.
We can always think of ways to spend somebody else's money, but also avoid the disappointments of unplanned crashes.
I would start with a bigger, better, faster hard drive, and cpu fan, then a more powerful, quieter power supply, then an optical drive... assuming the memory is maxed out.

upgrade

I am looking for speed more than anything here is the best I can do

Neither of these will help me determine memory demands... We need the motherboard brand and number from digits near the center of the board, or the brand and model of the computer.
It looks like a good, standard installation..
But a lot of such computers come with a 5400 rpm hard drive, and slower memory. Change to 7200 rpm and faster times can sometimes make a noticable difference.